| Patent application number | Description | Published |
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| 20110173009 | Apparatus and Method for Encoding/Decoding an Audio Signal Using an Aliasing Switch Scheme - An apparatus for encoding an audio signal includes the windower for windowing a first block of the audio signal using an analysis window having an aliasing portion and a further portion. The apparatus furthermore includes a processor for processing the first sub-block of the audio signal associated with the aliasing portion by transforming the sub-block from a domain into a different domain subsequent to windowing the first sub-block to obtain the processed first sub-block, and for processing a second sub-block of the audio signal associated with the further portion by transforming the second sub-block from the domain into the different domain before windowing the second sub-block to obtain a processed second sub-block. The apparatus furthermore includes a transformer for converting the processed first sub-block and the processed second sub-block from the different domain into a further different domain using the same block transform rule to obtain a converted first block which may then be compressed using any of the well-known data compression algorithms. Thus, a critically sampled switch between two coding modes can be obtained, since aliasing portions occurring in two different domains are matched to each other. | 07-14-2011 |
| 20110202354 | Low Bitrate Audio Encoding/Decoding Scheme Having Cascaded Switches - An audio encoder has a first information sink oriented encoding branch such as a spectral domain encoding branch, a second information source or SNR oriented encoding branch such as an LPC-domain encoding branch, and a switch for switching between the first encoding branch and the second encoding branch, wherein the second encoding branch has a converter into a specific domain different from the spectral domain such as an LPC analysis stage generating an excitation signal, and wherein the second encoding branch furthermore has a specific domain coding branch such as LPC domain processing branch, and a specific spectral domain coding branch such as LPC spectral domain processing branch, and an additional switch for switching between the specific domain coding branch and the specific spectral domain coding branch. An audio decoder has a first domain decoder such as a spectral domain decoding branch, a second domain decoder such as an LPC domain decoding branch for decoding a signal such as an excitation signal in the second domain, and a third domain decoder such as an LPC-spectral decoder branch and two cascaded switches for switching between the decoders. | 08-18-2011 |
| 20110238426 | Audio Decoder, Audio Encoder, Method for Decoding an Audio Signal, Method for Encoding an Audio Signal, Computer Program and Audio Signal - An audio decoder for providing a decoded audio information on the basis of an entropy encoded audio information includes a context-based entropy decoder configured to decode the entropy-encoded audio information in dependence on a context, which context is based on a previously-decoded audio information in a non-reset state-of-operation. The context-based entropy decoder is configured to select a mapping information, for deriving the decoded audio information from the encoded audio information, in dependence on the context. The context-based entropy decoder includes a context resetter configured to reset the context for selecting the mapping information to a default context, which default context is independent from the previously-decoded audio information, in response to a side information of the encoded audio information. | 09-29-2011 |
| 20120022881 | AUDIO ENCODER, AUDIO DECODER, ENCODED AUDIO INFORMATION, METHODS FOR ENCODING AND DECODING AN AUDIO SIGNAL AND COMPUTER PROGRAM - An audio decoder for providing a decoded audio information on the basis of an encoded audio information includes a window-based signal transformer configured to map a time-frequency representation, which is described by the encoded audio information, to a time-domain representation. The window-based signal transformer is configured to select a window, out of a plurality of windows including windows of different transition slopes and windows of different transform length, on the basis of a window information. The audio decoder includes a window selector configured to evaluate a variable-codeword-length window information in order to select a window for a processing of a given portion of the time-frequency representation associated with a given frame of the audio information. | 01-26-2012 |
| 20120158409 | Bandwidth Extension Encoder, Bandwidth Extension Decoder and Phase Vocoder - A bandwidth extension encoder for encoding an audio signal has a signal analyzer, a core encoder and a parameter calculator. The audio signal has a low frequency signal having a core frequency band and a high frequency signal having an upper frequency band. The signal analyzer is configured for analyzing the audio signal, the audio signal having a block of audio samples, the block having a specified length in time. The signal analyzer is furthermore configured for determining from a plurality of analysis windows an analysis window to be used for performing a bandwidth extension in a bandwidth extension decoder. The core encoder is configured for encoding the low frequency signal to acquire an encoded or frequency signal. The parameter calculator is configured for calculating bandwidth extension parameters from the high frequency signal. | 06-21-2012 |
| 20120265541 | AUDIO SIGNAL ENCODER, AUDIO SIGNAL DECODER, METHOD FOR PROVIDING AN ENCODED REPRESENTATION OF AN AUDIO CONTENT, METHOD FOR PROVIDING A DECODED REPRESENTATION OF AN AUDIO CONTENT AND COMPUTER PROGRAM FOR USE IN LOW DELAY APPLICATIONS - An audio signal encoder includes a transform-domain path which obtains spectral coefficients and noise-shaping information on the basis of a portion of the audio content, and which windows a time-domain representation of the audio content and applies a time-domain-to-frequency-domain conversion. The audio signal decoder includes a CELP path to obtain a code-excitation information and a LPD parameter information. A converter applies a predetermined asymmetric analysis window in both if a current portion is followed by a subsequent portion to be encoded in the transform-domain mode or in the CELP mode. Aliasing cancellation information is selectively provided in the later case. | 10-18-2012 |
| 20120271644 | AUDIO SIGNAL ENCODER, AUDIO SIGNAL DECODER, METHOD FOR ENCODING OR DECODING AN AUDIO SIGNAL USING AN ALIASING-CANCELLATION - An audio signal decoder includes a transform domain path configured to obtain a time-domain representation of a portion of an audio content on the basis of a first set of spectral coefficients, a representation of an aliasing-cancellation stimulus signal and a plurality of linear-prediction-domain parameters. The transform domain path applies a spectrum shaping to the first set of spectral coefficients to obtain a spectrally-shaped version thereof. The transform domain path obtains a time-domain representation of the audio content on the basis of the spectrally-shaped version of the first set of spectral coefficients. The transform domain path includes an aliasing-cancellation stimulus filter to filter the aliasing-cancellation stimulus signal in dependence on at least a subset of the linear-prediction-domain parameters. The transform domain path also includes a combiner configured to combine the time-domain representation of the audio content with an aliasing-cancellation synthesis signal to obtain an aliasing reduced time-domain signal. | 10-25-2012 |
| 20130090934 | APPARATUS AND METHOD FOR GENERATING A SYNTHESIS AUDIO SIGNAL AND FOR ENCODING AN AUDIO SIGNAL - An apparatus for generating a synthesis audio signal using a patching control signal has a first converter, a spectral domain patch generator, a high frequency reconstruction manipulator and a combiner. The first converter is configured for converting a time portion of an audio signal into a spectral representation. The spectral domain patch generator is configured for performing a plurality of different spectral domain patching algorithms, wherein each patching algorithm generates a modified spectral representation having spectral components in an upper frequency band derived from corresponding spectral components in a core frequency band of the audio signal. The spectral domain patch generator is furthermore configured to select a first spectral domain patching algorithm from the plurality of patching algorithms for a first time portion and a second spectral domain patching algorithm from the plurality of patching algorithm for a second different time portion in accordance with the patching control signal to obtain the modified spectral representation. | 04-11-2013 |
| 20130096930 | Multi-Resolution Switched Audio Encoding/Decoding Scheme - An audio encoder for encoding an audio signal has a first coding branch, the first coding branch comprising a first converter for converting a signal from a time domain into a frequency domain. Furthermore, the audio encoder has a second coding branch comprising a second time/frequency converter. Additionally, a signal analyzer for analyzing the audio signal is provided. The signal analyzer, on the hand, determines whether an audio portion is effective in the encoder output signal as a first encoded signal from the first encoding branch or as a second encoded signal from a second encoding branch. On the other hand, the signal analyzer determines a time/frequency resolution to be applied by the converters when generating the encoded signals. An output interface includes, in addition to the first encoded signal and the second encoded signal, a resolution information identifying the resolution used by the first time/frequency converter and used by the second time/frequency converter. | 04-18-2013 |
| 20130124215 | CODER USING FORWARD ALIASING CANCELLATION - A codec supporting switching between time-domain aliasing cancellation transform coding mode and time-domain coding mode is made less liable to frame loss by adding a further syntax portion to the frames, depending on which the parser of the decoder may select between a first action of expecting the current frame to have, and thus reading forward aliasing cancellation data from the current frame and a second action of not-expecting the current frame to have, and thus not reading forward aliasing cancellation data from the current frame. In other words, while a bit of coding efficiency is lost due to the provision of the new syntax portion, it is merely the new syntax portion which provides for the ability to use the codec in case of a communication channel with frame loss. Without the new syntax portion, the decoder would not be capable of decoding any data stream portion after a loss and will crash in trying to resume parsing. Thus, in an error prone environment, the coding efficiency is prevented from vanishing by the introduction of the new syntax portion. | 05-16-2013 |
| 20130332152 | APPARATUS AND METHOD FOR ERROR CONCEALMENT IN LOW-DELAY UNIFIED SPEECH AND AUDIO CODING - An apparatus for generating spectral replacement values for an audio signal has a buffer unit for storing previous spectral values relating to a previously received error-free audio frame. Moreover, the apparatus includes a concealment frame generator for generating the spectral replacement values, when a current audio frame has not been received or is erroneous. The previously received error-free audio frame has filter information, the filter information having associated a filter stability value indicating a stability of a prediction filter. The concealment frame generator is adapted to generate the spectral replacement values based on the previous spectral values and based on the filter stability value. | 12-12-2013 |
